A trocar assembly is a surgical instrument that is used to gain access to a body cavity. A trocar assembly generally comprises two major components, a trocar sleeve, composed of a trocar housing and a trocar cannula, and a trocar obturator. The trocar cannula, having the obturator inserted therethrough, is directed through the skin to access a body cavity. Once the body cavity is accessed, laparoscopic or arthroscopic surgery and endoscopic procedures may be performed. In order to penetrate the skin, the distal end of the trocar cannula is placed against the skin that has been previously cut with a scalpel. The trocar obturator is then used to penetrate the skin and access the body cavity. By applying pressure against the proximal end of the trocar obturator, the sharp point of the trocar obturator is forced through the skin until it enters the body cavity. The trocar cannula is inserted through the perforation/incision made by the trocar obturator and the trocar obturator is withdrawn, leaving the trocar cannula as an access way to the body cavity.
The proximal end portion of the trocar cannula is typically joined to a trocar housing that defines a chamber having an open distal end portion in communication with the interior lumen defined by the trocar cannula. Elongated surgical instruments axially extend into and are withdrawn from the trocar cannula through the proximal end portion of the chamber defined by the trocar housing.
As those skilled in the art will certainly appreciate, many trocar housings are formed with first and second housing members. The first housing member may include an instrument seal for providing a seal about an instrument inserted through the trocar housing, and the second housing member may include a zero closure seal assembly, such as a duckbill seal assembly, for preventing escape of insufflations gas when no instrument is inserted through the trocar. It will be understood by those skilled in the art that such instrument seals and duckbill seals are employed to prevent escape of insufflations gas in an axial (longitudinal) direction from the body cavity, through the trocar cannula and housing, to the outside environment (along a direction generally parallel to the long axis of the cannula of the trocar.)
The first and second housing members may be selectively coupled together in a way that the first and second members may be separated, one from the other, to facilitate various surgical procedures. For example, it is often desirable to remove the first housing member during the removal of a specimen. The removal of the first housing member allows the specimen to pass through only the duckbill seal assembly, instead of passing through both the duckbill seal assembly and the proximal seal assembly. This provides for easier specimen removal and less trauma to the specimen during the removal process. The above incorporated patent application US 2005/0070947 discloses a trocar housing assembly having a first housing member selectively coupled to a second housing member.
During certain surgical procedures, such as bariatric procedures, relatively high bending and/or torsional loads may be placed on the trocar housing, such as when an instrument is inserted through the trocar, and the instrument and/or trocar is manipulated (e.g. by applying a force or torque to the instrument or trocar to rotate or pivot the trocar within the perforation/incision) to access/reach the required tissue in high body mass index (BMI) patients.
While having separable first and second seal housing members provides for convenient specimen removal, the interface between the first and second sealing members may provide a potential radial leak path of insufflations gas, especially when bending or torsional loads are applied to the trocar housing.